SOURCE

function b42Str(b4) {
    let orignalStr = atob(b4);
    let str = decodeURI(orignalStr);
    console.log(str);
    return str;
}

function reconvert(str) {
    str = str.replace(/(\\u)(\w{1,4})/gi, function ($0) {
        return (String.fromCharCode(parseInt((escape($0).replace(/(%5Cu)(\w{1,4})/g, "$2")), 16)));
    });
    str = str.replace(/(&#x)(\w{1,4});/gi, function ($0) {
        return String.fromCharCode(parseInt(escape($0).replace(/(%26%23x)(\w{1,4})(%3B)/g, "$2"), 16));
    });
    str = str.replace(/(&#)(\d{1,6});/gi, function ($0) {
        return String.fromCharCode(parseInt(escape($0).replace(/(%26%23)(\d{1,6})(%3B)/g, "$2")));
    });

    return str;
}

function itoa(i)
{ 
   return String.fromCharCode(i);
}
         
var b4 = "eyJjb2RlIjoiMCIsInJlc3VsdCI6IjI5NTc5LDAsMjk1NzcsMCwyMDAyNywwLDI3NDkxLDAsMjk5ODMsMCwyMjgyNSwwLDIyNzY0LDAsMjIzMTcsMCwyOTU3OCwwLDI5NTgxLDAsIn0=";
var str = b42Str(b4);
var obj = JSON.parse(str);

var result = obj["result"]; // obj["result"]
var unicodes = result.split(",");
unicodes.length = unicodes.length - 1;
unicodes = unicodes.filter(function (data, index) {
    return data != 0;
});
console.log(unicodes)
var uniArray = unicodes.map(function(data, index){
    var value = parseInt(data);
    // hexString = value.toString(16);
    console.log(value);
    // yourNumber = parseInt(hexString, 16);
    return itoa(value);
});
// var unicodeStr = "\\u" + uniArray.join("\\u");
console.log(uniArray);
// var value = reconvert(unicodeStr);
// console.log(value);